Method of decomposing oil to olefins



Feb. e, 1940. T. NAGEL 2,188,982

METHOD 0F DEGMPOSING OIL T0 OLEFINS Fil'ed March 9, 1958 E INVENTOR BY Patented Feb. 6, 1940 .UNITED STATES PATENT OFFICE' 3 Claims.

This invention is directed to a method of decomposing oil to olens, namely: aliphatic lunsaturated hydrocarbons of the homologous series Cn Han. Oil is to be considered as crude petroleum or liquids derived from crude petroleum.

Broadly speaking, my invention provides a thermal process for decomposing hydrocarbons while subjected to several atmospheres pressure and preferably to partial pressure of the hydrol carbons in the order of atmospheric or lower. pressure, the pressure serving to overcomethe resistance to mass flow through subsequent operations of cooling, fractionating, etc., and consists in controlling the thermal process so as to de- 5 compose the hydrocarbons to decomposition' products composed of olens as 'the major hydrocarbons yield and prevent reactions producing polymer products at the expense of the high yield of oleiins.

o By the method of this invention i'or producing oleilns from oil, a close range decomposition temperature is attained to flash decompose the oil to decomposition hydrocarbons without polymerizing reactions Ataking place, -the decomposition :s products being shock cooled to .below the polymerizing temperature zone to retain the highly reactive oletlns as decomposition products and also to prevent further decomposition'.

Oil charging stocks heavier ,than the lower l0 boiling liquid derivatives or fractions of crude petroleum, namely, lheavier than the grades classed as light distillates' and gas oils may be preheated. Preheating can be effected byv direct heat exchange-shock cooling the decomposi- :5 tion products with the heavier oil charging stocks, or when the charging stock is preheated from` an external source of heat then the oil charging stock should be rapidly preheated while subjected to superatmospheric pressure, the prei lo heat temperatureto be slightly belowthe vaporizing temperature at the pressure to which the oili`s subjected, thereby to maintain the oil as a.

liquid. Preheating these' heavier oil charging stocks serves to prepare the oil'ior iiash; decoml5 position upon continuously dispersing th'e oil throughout a hot zone. l.

The oil charging stock is continuously injected into a continuously flowing hot' gas which contains sumcient heat for heat exchangeto the oil 50 to flash decompose the oil at a close range temperature within a temperature range from 1000 F. to 1600" -F. -At said close range temperature the hydrocarbons lof the oil are decomposed to decomposition hydrocarbons. the major portion-- 55 o! winch is oleiins. The mowing decomposition (ci. 28o- 883) products are continuously shock cooled to below 900` F.-mto prevent the highly reactive oleilns from reacting to polymer products.

The heating of the oil through the polymerizing reactions temperature zone to the desired 6 close range decomposition temperature and the cooling of the decomposition products to below the polymerizing reactions temperature zone are so controlled that only decomposition of the hydrocarbons takes place, therefore reactions,pro 10 ducing polymer products at the expense of a high yield of olefins, do not occur.

The said desired close range temperature to be attained by flash heating the oil to within a temperature range of from 1000 F. to 1600 F. 15v

depends upon the speciiic olen, of the openv chain homologous series (Cn H211), 'desired as the major yield decomposition hydrocarbon, so that thehigher the said close range temperature attained, within the temperature rangeA from 1000 20 F.` to 1600 F.. the lighter weight will be the speciilc olefin produced as the major yield decomposition hydrocarbon.

For example, where the charging stock is a straight run natural fuel .oil of 20 A. P. I., and '25 where the major yield decomposition hydrocarbon desired is ethylene, the temperature to be attained to ash decompose the oil ranges from 1400F. to 1600* F. At the higher temperatures,

from 1500 F., the only olen Iproduced as the $0 major yield decomposition hydrocarbon will be ethylene-the lightest weight olefinwhile atv the lower temperatures within the temperature range from 1400 F. to 1600 F. propylene will be minor A yield olen' products.

- 86 Should the olen desired as the major yield decomposition product be propylene, then the temperature to be attained to flash decompose the oil is in the order of say 1350o F. to 1400 F.- a narrower temperature range than when 40 vethylene is to be the major yield decompositionproduct.

As the desired major yield olefin gradually bee comes heavier.- namely, butylene, amylene.. hexylene, etc., the temperature to be attained to 45 flash decompose the oil to the desired olei'ln b ecomes lower and the range narrows, untilwhen' heptylene, for example, is the desired maior'- yield'decomposition hydrocarbon, the temperature to 'be attained to -ash decompose the oil 60 will be in theorder of 1150 F., near the low end ofthe said temperature range l:lrom 1000 l". to 1800 F.

In the practice of my improved method, and

when operating at the higher temperatures with- IS hydrocarbon products reduced to atmospheric temperature will be mostly liquids and predomi nantly olens.

When using A. P. I. oil as the charging stock, the oil may be preheated either by heatexchange shock-cooling the decomposition products or from an external source of heat. In the latter case the oil is subjected to superatmosg pheric pressure while being rapidly preheated to a temperature slightly below its vaporizing temperature at the pressure employed. The speciilc oil mentioned, for example, may be heated to a temperature not to exceed 900 F, in a pipe still oil heater at a pressure not less than 150 pounds per square inch. The continuous ow of hot gas used as a heat carrying medium, and heretofore referred to, into which the oil is continuously dispersed, can be generated by combustion Aoi oil or other source of combustion or can .be

generated within the oil decomposing chamber and consists principally of carbonmonoxide and nitrogen produced by continuous partial oxidation of free carbon and the higher boiling end portion of the oil charging stock with a controlled continuous supply of air to produce the reaction temperature and volume of owing gas required for heat exchange to ilash decompose'the oil, which is continuously injected into and dispersed throughout the continuously generated and continuously flowing heat-carrying gas, to the said selective close range temperature. i The drawing illustrates merely diagrammatically an apparatus which may be employed in practicing my invention.

Referring to the accompanying drawing and assuming that ethylene is the major yield decomposition hydrocarbon desired: Straight run natural fuel oil, for example, of 20 Baum gravity. is taken from a suitable source of supply I and continuously flows, at a pressure of not less than 150 pounds per square inch, through a pressure pipe still oil heater 2. The liquid oil is rapidly preheated in' the still to slightly below its Vaporizing'temperature, which at the pressure mentioned is in the order oi' 850 F. The preheated liquid oil is continuously dispersed into a hot zone or oil decomposing chamber and hot gas generator 3, the oil, inthe apparatus illustrated, being sprayed or atomized vertically downward in the form of ahollow cone, encountering increasing heat intensity as it flows countercurrent to a continuously upwardly ilowing heat-carrying gas with which the oil intermixes within the oil decomposing chamber and hot gas generator 3, the oil being ash decomposed by the heat-carrying gas. 'I'he heat-carrying gas `referred to is continuously generated in the lower part oi the heat insulated chamber 3 by partial oxidation of the free carbon and the higher boiling end portion of the oil charging stock with a, controlled continuous ow of air which enters near the base of the chamber 3, as shown at IIi. The volume of the heat-carry ing gas produced is so controlled that as it ows upward the descending oil is heated to a close range temperature in the order of 1500 F. and flash-decomposed to decomposition products, the

major hydrocarbons yield of which is ethylene,

as the flowing mixture is deilected and reaches the outlet 5 of the chamber 3. T he continuously iiowing decomposition products at outlet 5 are continuously shock cooled below polymerizing temperature by a cooling medium such as oil. steam, water, gas, etc. For example, Ioil may be continuously sprayed into and shock-cool the products of decomposition as shown at 6, to a .temperature in the order of 600 F. to prevent the ethylene reacting to polymer products at the expense oi the high yield-of etlrvlene. The cooled decomposition products lare continuously dischargedl through the outlet pipe 'L It will be seen from all of the lforegoing that I have provided for the selective production of' oleiins from oil, wherein decomposition of the oil to produce a desired olefin as the major yieldy decomposition product is eilected by dispersing the oil continuously into the hot gas resulting from continuous combustion of oil, whereby the.

oil injected into the resulting combustion product is dash-decomposed, the continuously flowing decomposition products being continuously shock-v cooled to below polymerizing temperature.

The above operating example of this process l for carrying out the method of producing oleflns from oil and the diagrammatic ow sheet serve merely as an illustration of the practice of this invention and may vary so long as the fundamental principles herein described are adhered to.

What I claim is: 1. The method of selectively producing' specific olens of the aliphatic hydrocarbon series Cul-hn .'as the 'major hydrocarbon yield resulting from decomposing oil, which method comprises continuously atomizing oil in a zone while introducing air lntothe zone peripherally thereof and adjacent the -base of the zone, continuously generating a hot gas in the zone, by partial oxidation of the higher boiling end portion and free carbon of the charging stock with. said air, the atomized oilbeing dispersed into said hot gas, and generation of said hot gas being so controlled that the oil is flash decomposed within the temperature range from 1000 F. to 1600 F. to decomposition hydrocarbons, the major hydrocarbon of which is a desired specific oleiln and continuously shock-cooling the flowing decomposition products to below 900 F. to prevent the said specic olen from reacting to polymer products.

2. The method of producing oleiins as the major hydrocarbons yield resulting from decomposing oil, which method comprises continuouslyatomizing oil in a zone while introducing air into the zone peripherally thereof and adjacent the base of the zone, continuously generating a hot gas in the zone by partial oxidation of the higher boiling end portion and free carbon of the charging stock with said air, the atomized oil moving countercurrent to and being' dispersed into said hot gas, and generation oi' said hot gas being so controlled that the oil is flash decomposed within the temperature range from 1000 F. to 1600 F. to decomposition hydrocarbons, the major portion of which. is olei'lns, and continuously shockcooling the liiowing decomposition products to below polymerizing reactions temperature to retain the olens.

' 3, The method of producing oleflns as the major hydrocarbons yield resulting from decomposing oil, which method comprises'continuously atomizing oil downwardly in a zo'ne while intro-v ducing air into the zone peripherally thereof and imv adjacent the base of the zone, continuously genn o'f the higher boiling end portion and vfree car- 'bon of the charging stock with said ai'r, the gas moving upwardly and the atomized. oil being dispersed thereinto, generation of said gas being s0 controlled that the oil is ash decomposed within vthev ytemperature range from 1000 F. to 1600 F.

to 'decomposition hydrocarbons, the maJor portion of which is olens, and continuously shockcooling the flowing decomposition products to below polymerizing reactions temperature to retain THEODORE NAGEL. 

